Field
The present disclosure relates generally to an interface between a host processor and a peripheral device such as a camera and, more particularly, to improving data rates on a camera control communication interface bus.
Background
Manufacturers of mobile devices, such as cellular phones, may obtain components of the mobile devices from various sources, including different manufacturers. For example, an application processor in a cellular phone may be obtained from a first manufacturer, while the display for the cellular phone may be obtained from a second manufacturer. The application processor and a display or other device may be interconnected using a standards-based or proprietary physical interface. For example, a display may provide an interface that conforms to a Camera Serial Interface standard specified by the Mobile Industry Processor Interface (MIPI) Alliance.
In one example, MIPI standards define a camera control interface (CCI) that uses a two-wire, bi-directional, half duplex, serial interface configured as a bus connecting a master and one or more slaves. Conventional CCI is compatible with a protocol used in a variant of the Inter-Integrated Circuit (I2C) bus and is capable of handling multiple slaves on the bus, with a single master. The CCI bus may include Serial Clock (SCL) and Serial Data (SDA) signals. CCI devices and I2C devices can be deployed on the same bus such that two or more CCI devices may communicate using CCI protocols, while any communication involving an I2C bus uses I2C protocols. Later versions of CCI can provide higher throughputs using modified protocols to support faster signaling rates.
In one example a CCI extension (CCIe) bus may be used to provide higher data rates for devices that are compatible with CCIe bus operations. Such devices may be referred to as CCIe devices, and the CCIe devices can attain higher data rates when communicating with each other by encoding data as symbols transmitted on both the SCL line and the SDA line of a conventional CCI bus. CCIe devices and I2C devices may coexist on the same CCIe bus, such that in a first time interval, data may be transmitted using CCIe encoding and other data may be transmitted in a different time interval according to I2C signaling conventions.
There exists an ongoing need for providing optimized communications on serial interfaces configured as a bus connecting master and slave components within a mobile device.